JP3137604B2 - Method for producing breathable film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an excellent tensile strength,
The present invention relates to a method for producing a breathable film having appearance, texture, and tear strength, and a film for a sanitary material and a film for a building material produced by the method.

[0002]

2. Description of the Related Art A breathable film having voids which are continuous (penetrated) by stretching a film made of a composition of an olefin resin and an inorganic filler in a uniaxial or biaxial direction is already known. When these films are manufactured to be thin and have a low draw ratio, it is known that local necking causes uneven thickness due to non-uniformity, which significantly impairs commercial value. For this reason, for example, a composition to which a known third additive is added has been proposed in JP-A-62-18435 and the like, and a film using this composition is used for sanitary materials such as disposable disposable diapers. Used in

[0003]

However, these resin compositions are effective in compensating for the above-mentioned drawbacks, but have the drawback that the stretchability during molding and the tear strength of the film when thinned are inferior. are doing. An object of the present invention is to provide a method for producing a breathable film which has solved these disadvantages.

[0004]

Means for Solving the Problems The present inventors have attained the above object, which comprises (a) a linear ethylene copolymer, (b) an inorganic filler and (c) a fatty acid ester, and have a good balance of various physical properties. The present invention was completed by obtaining a suitable breathable film.

That is, the present invention relates to (a) a linear ethylene copolymer 20 containing 1 to 20% by weight of a comonomer of ethylene and an α-olefin or diolefin having 6 or more carbon atoms.
To 80% by weight, (b) 80 to 20% by weight of an inorganic filler,
And (c) a resin composition in which 0.1 to 15 parts by weight of a saturated or unsaturated fatty acid ester having 9 to 40 carbon atoms is blended with respect to 100 parts by weight of the total of the components (a) and (b). ,
After being formed into a film, stretched,
The longitudinal tear strength according to ASTM D1922-61T is 10 g or more, the tensile strength (TD breaking point) according to ASTM D882-67 is 700 g / 15 mm width or more, JIS Z
The moisture permeability according to 0208-1973 is 5,100 g / m ^2.
This is a method for producing a breathable film having excellent appearance and texture for 24 hours or more.

The linear ethylene copolymer of the component (a) suitable for producing the breathable film of the present invention has a density of 0.9.
45 g / cm ³ or less, melt flow rate 0.1-20 g / 1
It is a linear low-density polyethylene (L-LDPE) having a comonomer content of 2 to 15% by weight and a boiling normal hexane extraction amount of 15% by weight or less, more preferably 0.
935 g / cm ³ or less, melt flow rate 0.1 to 10 g /
L-LDPE having a comonomer content of 2 to 10% by weight for 10 minutes and a boiling normal hexane extraction amount of 10% by weight or less.

[0007] Still more preferably, the density is 0.91.
0 to 0.935 g / cm ³ , melt flow rate 0.3 to 1
L-LDPE having 0 g / 10 min, a comonomer content of 3 to 10% by weight, and a boiling normal hexane extraction amount of 8.5% by weight or less
And the most preferable one has a density of 0.920 to 0.9.
30 g / cm ³ , melt flow rate 0.5-3 g / 10 minutes,
L-LDPE having a comonomer content of 3 to 10% by weight and a boiling normal hexane extraction amount of 5% by weight or less.

Here, the density is measured according to JIS K 6760-1971, and the melt flow rate is measured according to ASTM.
According to D1238 (190 ° C.), the comonomer content was measured by infrared spectroscopy. The measurement of the amount of boiling normal hexane was measured by the method described in Examples described later.

L-LDPE having a density below the above range is:
If the stretched film has a large decrease in air permeability and blocking resistance, and exceeds the above range, the tensile strength, tear strength and hand of the stretched film are deteriorated.

If the melt flow rate is lower than the above range, the moldability is poor, and if it is higher, the moldability and the strength of the stretched film are reduced.

Those having a comonomer content outside the above range are not preferred in view of the strength and rigidity of the stretched film.

When the boiling normal hexane extraction amount exceeds the above range, the stretched film has a large decrease in air permeability and blocking resistance.

Further, the comonomer may have 6 or more carbon atoms,
Preferably, 6 to 24 α-olefins or diolefins are used. When an α-olefin or diolefin having 5 or less carbon atoms is used in place of these comonomers, there is a drawback that stretchability during film production and tensile strength and tear strength of the stretched film are poor. Further, those having a flow ratio (measurement method described in Examples) of 6 to 10 are preferable in terms of tensile strength and tear strength of the stretched film.

Such a copolymer is obtained by adding hexene-1,4-methylpentene-1,
Octene-1, decene-1, dodecene-1, hexadecene-1, dococene-1,1,5-hexadiene, 1,7
-Octadienes, 1,9-decadienes and the like, obtained by copolymerizing one or more kinds. When two or more comonomers are copolymerized with ethylene, propylene, butene-1, and
An α-olefin or diolefin having 5 or less carbon atoms, such as 1,3-butadiene, can be used in an amount that does not significantly impair the effects of the present invention.

As a method for producing the copolymer, a pressure of 5 to 2,
Ethylene and the above-mentioned α-olefin are copolymerized under conditions of 500 kg / cm ² and a temperature of 50 to 300 ° C. using a Ziegler type, vanadium type or Kaminsky type catalyst. For example, a method described in JP-B-56-18132 is known.

In the present invention, in order to obtain particularly good tear strength MD and film appearance of the obtained stretched film, it is preferable to use a granular or powdery linear ethylene copolymer. Is 0.001 to 0.7 mm, preferably 0.01 to 0.6 mm, and the particle size distribution is 70% by weight or more for 1.68 mm or less, 50% by weight or more for 0.84 mm or less, and 1 for 0.21 mm or less. Granular or powdery linear ethylene copolymer having a weight percentage of at least 0.5% by weight, more preferably at least 70% by weight of at most 1.68mm, at least 50% by weight of at most 0.84mm and at least 10% by weight of at most 0.21mm. It is preferred to use coalescence.

Here, the measuring methods of the average particle size and the particle size distribution are as follows.

<Average Particle Size / Particle Size Distribution Measurement Method> (i) Definition The linear ethylene copolymer is subjected to particle size classification using standard sieves of various sizes, and the weight distribution is defined as the particle size distribution.

The weight average sieve size calculated using the weight percentages of the sieve sizes classified by the particle size is defined as the average particle size.

(Ii) Apparatus and instruments 1) Shaker 2) Standard sieve According to JIS Z8801 (3.5, 1
0.5, 20, 32, 48, 70, 145, 200, 3
50 each mesh sieve and receiver) 3) Fine balance

(Iii) Test method 1) The standard sieve and the receiver used are cleaned with a bristle brush, and then cleaned with an air blow. 2) Measure the weight of the sieve and the receiver (w1). Assemble each sieve in order from the one with the smaller opening at the bottom. 3) 100 g ± 5 g of the sample was weighed with a precision balance (w
2) Load the sample from the top. 4) Fix the sieve on a shaker and shake for 15 minutes. 5) Take out the sieve and determine the weight of each sieve containing the sample and the receiver (w).

(Iv) Calculation method 1) Particle size distribution The weight percentage of the fraction of each sieve is determined by the following equation. W = [(w−w1) / w2] × 100 where W: weight percent (wt%) of the separated material of each sieve w: weight (g) of each sieve and sample including the sample after shaking w1: Weight of each sieve and receiver (g) w2: Total weight of the sample (g) 2) Average particle size The average particle size is determined from the following formula using the weight percentage of the fraction of each sieve. D = Σ (Wn × dn) / 100 where, D: average particle size of sample (mm) Wn: weight percent of separated material of each sieve (wt%) dn: size of mesh of each sieve (mm)

When a linear α-olefin or a linear diolefin is used as a comonomer constituting the linear ethylene copolymer, a non-linear α-olefin or a non-linear Compared to the case where a chain diolefin is used, the resulting stretched film has a remarkably high tear strength MD, which is preferable.

The component (b) suitable for producing the film of the present invention has an average particle size of 10 μm or less, preferably 0.1 μm or less.
A granular inorganic filler having a bulk density of 0.1 to 0.7 g / cm ³ , preferably 0.2 to 0.6 g / cm ³ , more preferably 0.1 to 5 μm, more preferably 0.5 to 2 μm. 3 ~
It is 0.5 g / cm ³ . Here, in order to obtain the average particle diameter, the specific surface area is measured by an air permeation method, and is calculated by the following equation. dm: average particle diameter (μm) dm = 60,000 / (ρ · Sw) ρ: true specific gravity of powder (g / cm ³ ) Sw: specific surface area of powder (cm ² / g)

As an apparatus for measuring the specific surface area, for example, a Shimadzu SS-100 powder specific surface area measuring apparatus can be used, and the specific surface area is obtained by applying the Kozeny-Carman equation.

The bulk density is measured according to JIS K
5101.

If the average particle size is larger than the above range, the appearance of the stretched film is impaired, and in the case of producing a thin stretched film having a thickness of 100 μm or less, perforations are caused.
Uneven stretching occurs, and stable stretchability is impaired. If the bulk density is below the above range, the air permeability of the stretched film is reduced, and if it is higher, the tensile strength is impaired. "granular"
Is a sphere, a square shape or a shape close to this,
It is not needle-shaped, rod-shaped or plate-shaped. If the shape of the inorganic filler is needle-like, rod-like, or plate-like, satisfactory microvoids cannot be imparted to the stretched film.

Examples of such inorganic fillers include calcium carbonate, calcium oxide, zeolite, amorphous aluminosilicate, clay, synthetic silica, titanium oxide, alumina, barium sulfate, aluminum sulfate, magnesium hydroxide and the like. Calcium, zeolite,
Amorphous aluminosilicate, barium sulfate, synthetic silica, magnesium hydroxide and the like are preferable, and calcium carbonate and barium sulfate are particularly preferable. These can be used alone or 2
A mixture of more than one species can be used. The water content of the inorganic filler (b) is 3,000 ppm or less,
Those having 0 ppm or less are preferred. If the water content exceeds this, the foaming phenomenon is apt to occur, and stable film forming becomes difficult, poor hue and poor appearance of the film and the like, and the filler is liable to secondary aggregation, thereby further poor appearance. In addition, poor stretching tends to occur.

The component (c) suitable for producing the film of the present invention is a saturated or unsaturated fatty acid ester having 9 to 40 carbon atoms. Specific examples of the unsaturated fatty acid ester include (poly) ethylene Glycol oleate, (poly) propylene glycol oleate, glyceryl oleate, sorbitan oleate, (poly) ethylene glycol sorbitan oleate, butyl oleate, pinacol oleate, m-cresol oleate, pentaerythritol oleate, glyceryl Linolenate, glyceryl ricinolate, methyl ricinolate, ethyl ricinolate, butyl ricinolate, methyl acetyl ricinolate, ethyl acetyl ricinolate, butyl acetyl ricinolate, (poly) ethylene glycol ricinolate, glyceryl acenoate Rurishinoreto, mention may be made of glyceryl Ersi benzoate and the like. Among them, glyceryl hydroxy fatty acid esters are preferred, and glyceryl ricinoleate is particularly preferred.

Specific examples of the saturated ester include:
(Poly) ethylene glycol laurate, (poly) propylene glycol laurate, glyceryl laurate,
Sorbitan laurate, (poly) ethylene glycol sorbitan laurate, glyceryl myristate, glyceryl palmitate, butyl stearate, ethylene glycol stearate, propylene glycol stearate, pinacol stearate, m-cresol stearate, (poly) ethylene glycol Stearate, (poly) propylene glycol stearate, glyceryl stearate, pentaerythritol stearate, sorbitan stearate, (poly) ethylene glycol sorbitan stearate, methylhydroxystearate,
Ethyl hydroxystearate,

Butylhydroxystearate, methylacetylhydroxystearate, ethylacetylhydroxystearate, butylacetylhydroxystearate, ethylene glycol hydroxystearate, propylene glycol hydroxystearate, pinacol hydroxystearate, m-cresol hydroxystearate , (Poly) ethylene glycol hydroxystearate, (poly) propylene glycol hydroxystearate, pentaerythritol hydroxystearate, sorbitan hydroxystearate, ethylene glycol sorbitan hydroxystearate, glyceryl hydroxystearate, glyceryl acetylhydroxystearate and the like. be able to.

Among them, ethylene glycol hydroxystearate, propylene glycol hydroxystearate, pinacol hydroxystearate, m-cresol hydroxystearate, (poly) ethylene glycol hydroxystearate, (poly) propylene glycol hydroxystearate, pentaerythritol hydroxystearate Glyceryl hydroxy saturated fatty acid esters such as glyceryl hydroxystearate, ethylene glycol sorbitan hydroxystearate, glyceryl hydroxystearate and glyceryl acetyl hydroxystearate are preferred. Most preferred is glyceryl hydroxystearate, especially glyceryl-12-hydroxystearate.

When a saturated ester is used as a fatty acid ester, compared with the case where an unsaturated ester is used,
It is more preferable because there is almost no smoke during molding and the obtained stretched film is excellent in odorlessness.

The mixing ratio of each of the components (a), (b) and (c) is as follows.
Component (a) is 20 to 80% by weight and component (b) is 80 to 20% by weight, preferably 30 to 70% by weight of component (a), based on the total amount of component (a) and component (b). b) 70-30% by weight of component, more preferably 35-35% of component (a)
60% by weight and 65 to 40% by weight of the component (b). For a total of 100 parts by weight of the components (a) and (b),
Component (c) is 0.1 to 15 parts by weight, preferably 0.5 to 15 parts by weight.
7 parts by weight, more preferably 1 to 5 parts by weight.

If the component (b) is below the above range, the air permeability and texture of the stretched film are reduced, and if it exceeds the above range, the stretchability during film production, or the tensile strength and tear strength of the stretched film are reduced. This leads to disadvantages such as deterioration of the commercial value.

When the component (c) is below the above range, when a stretched film is manufactured to be thin and has a low stretching ratio, local necking causes uneven thickness due to unevenness, which significantly impairs commercial value. Conversely, if the ratio exceeds the above range, the moldability decreases, and the breathability and blocking resistance of the stretched film are undesirably reduced.

The tensile strength, air permeability, appearance,
In order to make the balance between the feel, the stretchability and the tear strength particularly good, preferably, the above-mentioned granular or powdery component is used as the component (a), and the component (a) and the component (b) are mixed. The mixture was mixed well with a blender such as a Henschel mixer, and the mixture was further added with the component (c). The mixture was melt-kneaded with a twin-screw kneading extruder, a Banbury mixer or a kneader, and then pelletized. It is desirable to use a composition.

In the present invention, antioxidants, stabilizers, dispersants, lubricants, antiblocking agents, pigments, antifogging agents, antistatic agents, ultraviolet absorbers, light stabilizers, and nuclei commonly used in the composition. An additive such as an agent may be blended.

Linear ethylene such as a copolymer of ethylene and an α-olefin or diolefin having 5 or less carbon atoms, a high-pressure low-density polyethylene, a high-density polyethylene, a polypropylene, a polybutene, and an ethylene-vinyl acetate copolymer. Resins and rubber components other than the copolymer (a) may be blended as long as the effects of the present invention are not significantly impaired.

In the present invention, the above composition is formed into a film such as a film, sheet or tape by T-die molding, inflation molding or the like, and then stretched uniaxially or biaxially at a normal stretching temperature. To manufacture breathable films such as films for sanitary materials and films for building materials. This stretching method may be a conventionally known method, specifically, flat roll stretching, oven stretching or tube stretching in uniaxial stretching, and flat tenter stretching or tube stretching in biaxial stretching. Methods such as inflation stretching and mandrel stretching. The stretching ratio is 1.2 to 6.0 times, preferably 1.2 to 4.0.
0 times is suitable.

The thickness of the obtained film is 5 to 300 μm.
m, preferably 10 to 50 μm is practical.

The film obtained in this manner is AS
10 g of tear strength MD according to TM D1922-61T
Or more, preferably 15 g or more, particularly preferably 2 g or more.
0 g or more. If the film has a tear strength MD below this range, it cannot be satisfactorily applied to the intended use of the present invention. Further, the tensile strength (TD breaking point) according to ASTM D882-67 is 700 g / 15 mm width or more.
The moisture permeability according to IS Z0308-1973 is 5,100.
g / m ² · 24 hr or more, with excellent appearance and texture.

[0043]

The breathable film of the present invention has good stretchability at the time of film production, particularly excellent tear strength, and balances tensile strength, air permeability, appearance and texture. Therefore, it is useful for sanitary materials such as disposable diapers, sanitary articles, and medical clothing, and for building materials such as anti-condensation materials.

When a saturated fatty acid ester is used as the component (c), there is almost no smoke during molding, and the resulting film has excellent odorlessness.

[0045]

【Example】

Examples 1 to 3 and Comparative Examples 1 to 6 An ethylene copolymer corresponding to the component (a) shown in Table 1,
First, using the inorganic filler of the component (b) and the fatty acid ester of the component (c), the components (a) and (b) are mixed with a Henschel mixer, and the component (c) is added and mixed. The mixture was extruded at a temperature of 200 ° C. using a shaft kneading extruder (screw diameter: 65 mm) to obtain pellets of each composition. In Comparative Example 6, as the component (a), polyethylene produced by a high-pressure radical polymerization method was used.

[0046]

[Table 1]

[0047]

[Table 2]

Each of these compositions was processed into a film by the following method. An extruder (screw diameter 50 mm, L /
D24) and T-die (300mm width, lip width 1.2mm)
The film was extruded into a film at 230 ° C., and was uniaxially stretched at a stretching temperature of 85 ° C. and a stretching magnification of 3 times with a short section hot stretching roll to produce a 30 μm thick breathable film.

The quality of the film thus obtained was evaluated for the following items. The measuring method is as follows.
The evaluation results are shown in Table 2.

The melt flow rate (MFR) is
According to ASTM D1238 (190 ° C.), the flow ratio (FR) is determined according to JIS K 7210-1975.
(190 ° C.) using a melt indexer and based on the following equation. FR = (MFR under load of 10 kg) / (MFR under load of 2.16 kg)

The average particle size of the filler is determined by the Coulter counter method (dispersion method is 28 KC ultrasonic for 5 minutes,
0.01% sodium hexametaphosphate).

Amount of boiling normal hexane extracted 5 g of a film extruded to a film thickness of 30 μm at 200 ° C. by air-cooled inflation molding was put in a cylindrical filter paper, and then extracted at a boiling point for 8 hours by a Soxhlet extraction device injected with 200 ml of normal hexane. I do. After drying the cylindrical filter paper with a vacuum dryer for 60 minutes, the weight loss is measured.

The composition was extruded using an extruder (screw diameter 50 mm, L / D 24) and a T-die (300 mm width, lip width 1.2 mm).
The film is extruded at 30 ° C., and is uniaxially stretched at a stretching temperature of 85 ° C. with a short-section hot stretching roll, and the maximum stretching ratio at which the film is cut is measured.

Tensile strength Measured according to ASTM D882-67.

Moisture permeability Measured in accordance with JIS Z 0208-1973.

Tear strength Measured according to MD ASTM D1922-61T.

Odor The formed film was cut and 30 g was placed in an Erlenmeyer flask, which was evaluated by a sensory test. A: Almost no odor B: Slightly odor C: Smell

Smoke emission The presence or absence of smoke emission during film formation was evaluated.

Film Appearance Test An abnormal appearance (striation, unevenness, bumps, etc.) on the surface of the formed film was visually observed. A: good B: slightly bad C: extremely bad

[0060]

[Table 3]

Examples 4 to 8 and Comparative Examples 7 to 12 Except that ethylene copolymers having various particle size distributions shown in Table 2 were used instead of the ethylene copolymer corresponding to the component (a), Each composition was obtained in the same manner as in Examples 1 to 3, processed into a film and evaluated in the same manner as in Examples 1 to 3. The evaluation results are shown in Table 3.

[0062]

[Table 4]

[0063]

[Table 5]

Examples 9 to 11 and Comparative Examples 13 and 14 Examples 1 to 3 were repeated except that the ethylene copolymer shown in Table 3 was used instead of the ethylene copolymer corresponding to the component (a).
Each of the compositions was obtained in the same manner as described above, and processed and evaluated in the same manner as in Examples 1 to 3. The evaluation results are shown in Table 4 together with the above examples so that the types of comonomer can be compared.

[0065]

[Table 6]

[0066]

[Table 7]

Examples 12 and 13 and Comparative Examples 15 and 17 The ethylene copolymer of the component (a) shown in Table 4 and (b)
Using the inorganic filler of the component and the fatty acid ester of the component (c), respective compositions were obtained in the same manner as in Examples 1 to 3, and processed and evaluated in the same manner as in Examples 1 to 3. Table 5 shows the evaluation results.

[0068]

[Table 8]

[0069]

[Table 9]

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁷ Identification code FI A61F 13/514 C08K 5/10 C08F 210/02 C08L 23/08 C08K 3/00 A41B 13/02 F 5/10 A61F 13/18 320 C08L 23/08 B29K 23:00 105: 04 B29L 7:00 (72) Inventor Hideo Uchiyama 1 Tohocho, Yokkaichi-shi, Mie Prefecture Mitsubishi Yuka Corporation Yokkaichi Research Institute (56) References JP-A-63-63 43932 (JP, A) JP-A-62-141041 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 9/00-9/42 B29C 55/02 C08J 5/18

Claims (4)

(57) [Claims] (1) 2 to 15% by weight of a comonomer of ethylene and an α-olefin or diolefin having 6 or more carbon atoms
20 to 80% by weight of a linear ethylene copolymer, (b) 80 to 20% by weight of an inorganic filler, and (c) a saturated or unsaturated fatty acid ester having 9 to 40 carbon atoms, the component (a) and (b) A method for producing a breathable film, comprising: forming a resin composition containing 0.1 to 15 parts by weight, based on a total of 100 parts by weight of components, into a film, and then stretching the film. Component (a) has a density of 0.945 g · cm ³ or less, a melt flow rate of 0.1 to 20 g / 10 min, a boiling normal hexane extraction amount of 15% by weight or less, and an average particle size of 0.001 to 0. 0.7 mm, particle size distribution: 1.68 mm or less is 70% by weight or more, 0.84
mm or less is 50% by weight or more, 0.21mm or less is 1.5% by weight or more and 35% by weight or less, and is a granular or powdery linear polyethylene copolymer.
Method. 2. The method for producing a breathable film according to claim 1, wherein the film is stretched at a stretching ratio of 1.2 to 6 times. 3. A film for a sanitary material produced by the method according to claim 1. 4. A building material film produced by the method according to claim 1.